Apparatus for separating magnetic particles from liquids containing said particles, and an array of vessels suitable for use with such an apparatus

ABSTRACT

An apparatus for separating magnetic particles from a liquid which contains said particles, said liquid being contained in an elongated vessel ( 11 ) having a length axis ( 12 ), said vessel being arranged in a vessel holder ( 13 ) with its length axis ( 12 ) in a substantially vertical position, said vessel ( 11 ) having a bottom and a tapered cross-section that diminishes towards the bottom of the vessel and a side wall ( 14 ) which has an outer surface which forms an angle with the length axis ( 12 ) of said vessel ( 11 ). This apparatus comprises a magnet ( 15 ) having a plane outer surface ( 16 ) and being adapted for being moved by transport means ( 17 ) along a motion path ( 25 ), said magnet ( 15 ) and said transport means ( 17 ) being so arranged with respect to said vessel ( 11 ) that over a portion of said motion path ( 25 ) said plane outer surface ( 16 ) of said magnet is in contact with a portion of said outer surface of said side wall ( 14 ) of said vessel ( 11 ), and transport means ( 17 ) for moving said magnet ( 15 ) between a first predetermined position and a second predetermined position along said motion path ( 25 ).

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a divisional of application Ser. No. 12/294,509,filed Jun. 28, 2010, now U.S. Pat. No. 8,470,267 which was a nationalstage filing under 35 U.S.C. 371 of PCT/EP2007/002491, filed Mar. 21,2007, which claims the benefit of priority from EP 06075785.3, filedMar. 31, 2006, the contents of which are incorporated by referenceherein in their entirety.

FIELD OF THE INVENTION

The present application relates to the field of devices for magneticseparation of an analyte from a liquid sample as used for example inimmuno- or nucleic acid diagnostic assays.

BACKGROUND OF THE INVENTION

Magnetic particles are used as solid phase for performing somediagnostic assays, e.g. immunoassays. Such assays comprise magneticparticles in suspension in a reaction solution contained in a vessel.When the assay is conducted, it is at some steps necessary to separatethe magnetic particles from the liquid contained in the vessel.

In a known apparatus this is done by attracting the magnetic particlesto the walls of the vessel by means of a magnet positioned close to theouter side wall of the vessel and by extracting the liquid from thevessel by suitable means.

In an apparatus of this kind described in U.S. Pat. No. 6,187,270 apipetting tip is used as a vessel and a magnet is located close to awall of the pipetting tip in order to fix a cluster of magneticparticles at a given position on the inner surface of that wall of thepipetting tip. With the cluster of magnetic particles in that positionwashing water is drawn into the pipetting tip for performing a washingstep. This water is ejected from the pipetting tip and another portionof fresh water is drawn in. After that the pipetting tip is slowly movedaway from the magnet for moving the magnetic particles towards the tipof the pipetting tip.

According to U.S. Pat. No. 6,187,270 a stationary magnet is used and anapparatus for moving the pipetting tip with respect to the magnet isused for carrying out the above described motion of the pipetting tip. Adisadvantage of the latter apparatus is that the magnetic force thatacts on the magnetic particles rapidly diminishes as the pipetting tipis moved away from the magnet, and the desired transport of the magneticparticles to the tip of the pipetting tip is thus relatively slow.

Another disadvantage of an apparatus of the kind described in U.S. Pat.No. 6,187,270 is that when it is desired to process in parallel liquidscontained in a plurality of vessels, a corresponding plurality oftransport means for moving the vessels away from the magnets arerequired.

SUMMARY OF THE INVENTION

In a first aspect the invention relates to a method for separatingmagnetic particles from a liquid which contains said particles, saidliquid being contained in an elongated vessel, said method comprisingautomatically moving a magnet along a motion path with respect to saidelongated vessel, wherein the elongated vessel has a length axis and isarranged in a vessel holder with its length axis in a substantiallyvertical position, said vessel having a bottom and a lower portion whichhas a tapered cross-section that diminishes towards the bottom of thevessel and a side wall which has an outer surface which forms an anglewith the length axis of said vessel, and wherein, the magnet has a planeouter surface in contact with a portion of the outer surface of the sidewall of the lower portion of said vessel over a portion of said motionpath, and wherein the magnet is moved downwards and towards the lengthaxis of said vessel, when it is moved along said portion of said motionpath.

In another aspect, the invention relates to an apparatus for separatingmagnetic particles from a liquid which contains said particles, saidapparatus comprising an elongated vessel which contains said elongatedvessel having a length axis and a bottom, said vessel being arranged ina vessel holder with its length axis in a substantially verticalposition, said vessel having a lower portion which has a taperedcross-section that diminishes towards the bottom of the vessel and aside wall which has an outer surface which forms an angle with thelength axis of said vessel, a magnet having a plane outer surface andbeing adapted for being moved by transport means along a motion path,said magnet and said transport means being so arranged with respect tosaid vessel that over a portion of said motion path said plane outersurface of said magnet is in contact with a portion of said outersurface of said side wall of said lower portion of said vessel, andtransport means for moving said magnet between a first predeterminedposition and a second predetermined position along said motion path,said motion path being so arranged that said magnet is moved downwardsand towards the length axis of said vessel when said magnet is movedfrom said first predetermined position to said second predeterminedposition along said motion path.

In a further aspect, the invention relates to an array of vesselssuitable for containing liquid samples to be processed in an analyzer,said array comprising a first row of vessels for receiving said samples,a second row of vessels each of which is adapted for receiving apipetting tip, an upper part having a substantially cuboid shape andbeing divided in compartments having each side walls and a bottom wall,a vessel for receiving a sample and a vessel for receiving a pipettingtip extending from respective openings in the bottom wall of each ofsaid compartments, each of said compartments having a back side wall anda front side wall located in face of the back side wall, saidcompartments being separated from each other by side walls which extendeach between a back side wall and a front side wall of a compartment,and each of said front side walls having a central opening which allowsthe passage of the tip of a pipetting tip when the latter is moved froma position within the array of vessels to a position outside the arrayof vessels.

In yet another aspect, the invention relates to an apparatus forseparating magnetic particles from a plurality of liquids which containsaid particles, each of said liquids being contained in a vessel whichis part of an array of vessels, an array of vessels according to theinvention and a connecting device for connecting said array of vesselsto means for disposal of waste liquids contained in vessels of saidarray of vessels.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows a perspective view of an apparatus according to theinvention.

FIG. 2 shows a cross-sectional view of the apparatus shown in FIG. 1 ina plane passing through the length symmetry axis of vessel 11 in FIG. 1.

FIG. 3 shows a perspective view of an array 34 of a first embodiment ofmagnet holders 18 each of which holds a magnet 15.

FIG. 4 shows a perspective view of a second embodiment of a magnetholder 18 for holding a plurality of magnets 15.

FIG. 5 shows a cross-sectional view of a first embodiment of a magnetholder 18 shown in FIG. 1 and of a magnet 15 inserted thereinto.

FIG. 6 shows a cross-sectional view of a second embodiment of a magnetholder 18 shown in FIG. 1 and of a magnet 15 inserted thereinto.

FIG. 7 shows a first, exploded perspective view of a vessel array 41according to the invention, waste connector 71 and pipetting tip 61.

FIG. 8 shows a perspective view of a vessel array 41 according to theinvention with pipetting tips 61 inserted in respective vessels 51 eachof which is adapted for receiving a pipetting tip.

FIG. 9 shows a second perspective view of a vessel array 41 according tothe invention.

FIG. 10 shows a cross-sectional view of vessel array 41.

FIG. 11 shows a perspective view of a pipetting tip 61, as shown inFIGS. 1 and 2.

FIG. 12 shows a schematic cross-sectional view of a certain embodimentof the lower part 74 of waste connector 71.

DETAILED DESCRIPTION OF THE INVENTION

A first aim of the invention is therefore to provide a method and anapparatus which makes possible to transport magnetic particles within avessel more rapidly.

A second aim of the invention is to provide a method and an apparatuswhich makes it possible to achieve the above mentioned first aimsimultaneously in a plurality of vessels.

A third aim of the invention is to provide an apparatus which inaddition to achieving the above-mentioned second aim makes possible theremoval of waste liquids contained in a plurality of vessels with moresimple means than in prior art.

A fourth aim of the invention is to provide an array of vessels suitablefor use with apparatus of the above-mentioned kind.

According to a first aspect of the invention the above-mentioned firstaim is achieved with a method according to claim 1 and with an apparatusaccording to claim 4. Further embodiments of the latter method aredefined by claims 2 and 3. Further embodiments of the apparatusaccording to claim 4 are defined by claims 5 to 9.

According to a third aspect of the invention the above-mentioned thirdaim is achieved with an apparatus according to claim 12.

According to a fourth aspect of the invention the above-mentioned fourthaim is achieved with a vessel array according to claim 10. A certainembodiment of this vessel array is defined by claim 11.

The apparatuses according to the invention offer the advantage ofproviding the possibility of carrying out washing steps of theabove-described type more rapidly, more effectively and with moreefficient means, in particular in the case of parallel processing ofliquids which contain magnetic particles and which are contained in aplurality of vessels.

The vessel array according to the invention is particularly advantageousfor use with an apparatus according to the second aspect of theinvention.

The term “cuboid” means approximately cubical in shape, as defined inMerriam-Webster Collegiate Dictionary, Tenth Edition.

The invention concerns a method for separating magnetic particles from aliquid which contains said particles, said liquid being contained in anelongated vessel having a length axis, said vessel being arranged in avessel holder with its length axis in a substantially vertical position,said vessel having a bottom and a lower portion which has a taperedcross-section that diminishes towards the bottom of the vessel and aside wall which has an outer surface which forms an angle with thelength axis of said vessel.

The invention further concerns a method for separating magneticparticles from a plurality of liquids which contain said particles, eachof said liquids being contained in an elongated vessel which has alength axis and which is part of an array of vessels, the vessels ofsaid array of vessels being arranged in a vessel holder with theirlength axis in a substantially vertical position, each of said vesselshaving a bottom and a lower portion which has a tapered cross-sectionthat diminishes towards the bottom of the vessel and a side wall whichhas an outer surface which forms an angle with the length axis of saidvessel.

The invention also concerns an apparatus for separating magneticparticles from a liquid which contains said particles, said liquid beingcontained in an elongated vessel having a length axis, said vessel beingarranged in a vessel holder with its length axis in a substantiallyvertical position, said vessel having a bottom and a lower portion whichhas a tapered cross-section that diminishes towards the bottom of thevessel and a side wall which has an outer surface which forms an anglewith the length axis of said vessel.

The invention further concerns an apparatus for separating magneticparticles from a plurality of liquids which contain said particles, eachof said liquids being contained in an elongated vessel which has alength axis and which is part of an array of vessels, the vessels ofsaid array of vessels being arranged in a vessel holder with theirlength axis in a substantially vertical position, each of said vesselshaving a bottom and a lower portion which has a tapered cross-sectionthat diminishes towards the bottom of the vessel and a side wall whichhas an outer surface which forms an angle with the length axis of saidvessel

The invention further concerns an array of vessels suitable forcontaining liquid samples to be processed in an apparatus of theabove-described kind.

The subject invention will now be described in terms of its variousembodiments with reference to the accompanying drawings. Theseembodiments are set forth to aid the understanding of the invention, butare not to be construed as limiting.

EXAMPLES

The following examples and figures are provided to aid the understandingof the present invention, the true scope of which is set forth in theappended claims. It is understood that modifications can be made in theprocedures set forth without departing from the spirit of the invention.

Example 1 First Embodiment of an Apparatus According to the Invention

A first embodiment of an apparatus for separating magnetic particlesfrom a liquid which contains such particles is described hereinafterwith reference to FIGS. 1, 2, 5 and 6.

The apparatus shown in FIGS. 1 and 2 comprises a vessel holder 13. Aliquid which contains magnetic particles is contained in an elongatedvessel 11 shown in FIGS. 1 and 2.

Vessel 11 has a length symmetry axis 12 and has a lower portion whichincludes the bottom part of vessel 11. The lower portion of vessel 11has a tapered cross-section that diminishes towards the bottom of thevessel. The lower portion of vessel 11 has a side wall 14. Side wall 14has an outer surface which has a conical shape. Therefore, theintersection of the outer surface of side wall 14 with a plane thatpasses through the length axis 12 of vessel 11 forms a small angle withthe length axis 12.

Vessel 11 is arranged in vessel holder 13 with the length axis 12 ofvessel 11 in a substantially vertical position.

The apparatus shown in FIGS. 1 and 2 further comprises a magnet 15 whichhas a plane outer surface 16, and transport means 17 for moving magnet15 along a motion path 25. As shown by FIG. 2, motion path 25 is forexample a closed motion path.

Transport means 17 comprise a magnet holder 18 for receiving and holdinga substantial portion of magnet 15 and a belt-drive 19 for moving magnetholder 18 and thereby magnet 15 along motion path 25. The structure ofthe belt drive includes tooth wheels 27 and 28 and a tension pulley 29in the arrangement shown by FIG. 2. An initial tension of belt-drive 19is achieved by adjustment of the position and radius of tension pulley29.

Transport means 17 are adapted for moving magnet 15 between a firstpredetermined position and a second predetermined position along motionpath 25. As shown by FIG. 2, the first predetermined position lies e.g.at about the same height as the central part of the lower portion ofvessel 11, and the second predetermined position is e.g. close to thebottom of vessel 11.

Magnet 15 and transport means 17 are so arranged with respect to vessel11 that while transport means 17 move magnet 15 along the portion ofmotion path 25 which extends from the first predetermined position tothe second predetermined position, the plane outer surface 16 of magnet15 is in contact with a portion of the outer surface of side wall 14 ofthe lower portion of vessel 11. Motion path 25 is so arranged thatmagnet 15 is moved downwards and towards the length axis 12 of vessel 11when magnet 15 is moved from said first predetermined position to saidsecond predetermined position along motion path 25.

As shown by FIGS. 5 and 6, magnet holder 18 has a cavity 21 forreceiving a portion of magnet 15.

In a certain embodiment a portion of magnet 15 is arranged in andsnuggly fits in a cavity 21 of magnet holder 18 as shown by FIG. 6. Inthis embodiment transport means 17 are so dimensioned that the initialtension of belt-drive 19 exerts on magnet 15 a force which presses itagainst side wall 14 and which is sufficient for ensuring contact of theplane outer surface 16 of magnet 15 and the outer surface of side wall14 of the lower portion of vessel 11, when the magnet 15 is locatedbetween belt-drive and vessel 11 and moves along motion path 25.

In another embodiment of magnet holder 18 shown by FIG. 5, the structureof this holder includes leaf springs 22 and 23 arranged between magnet15 and magnet holder 18. In this embodiment the force that pressesmagnet 15 against the outer surface of side wall 14 of the lower part ofvessel 11 is the sum of the force resulting from the initial tension ofbelt drive 19 and the additional force exerted by leaf springs 22 and23. The force resulting from this sum ensures a good contact of theplane outer surface 16 of magnet 15 and the outer surface of side wall14 of the lower portion of vessel 11, when the latter is located betweenbelt-drive and vessel 11 and moves along motion path 25.

As illustrated by FIG. 5, in a certain embodiment magnet 15 has amagnetic axis 24 that forms an angle of 45 degrees with plane outersurface 16 of the magnet 15.

Example 2 First Embodiment of a Method According to the Invention

A method for separating magnetic particles from a liquid which containssuch particles can be carried out according to the invention with theapparatus embodiment of example 1 described above with reference toFIGS. 1, 2, 5 and 6. According to this method a magnet 15 having a planeouter surface 16 is moved automatically along a motion path 25 so thatover a portion of motion path 25 which extends from the above-mentionedfirst predetermined position to the second predetermined position, theplane outer surface 16 of magnet 15 is in contact with a portion of theouter surface of side wall 14 of the lower portion of vessel 11, andmagnet 15 is moved downwards and towards the length axis 12 of vessel11, when it is moved along the above mentioned portion of motion path25.

In a certain embodiment a force is exerted on magnet 15 in order topress the plane outer surface 16 of magnet 15 on the outer surface ofthe side wall 14 of the lower part of vessel 11 while magnet 15 is movedalong the above-mentioned portion of motion path 25.

In a certain embodiment motion path 25 is a closed motion path.

Example 3 Second Embodiment of an Apparatus According to the Invention

A second embodiment of an apparatus for separating magnetic particlesfrom a plurality of liquids which contain such particles is describedhereinafter with reference to FIGS. 1 to 7.

The apparatus shown in FIGS. 1 and 2 comprises a vessel holder 13adapted for receiving an array 31 of vessels 11. Each of the liquidswhich contain magnetic particles is contained in one of vessels 11.

Each vessel 11 has a length symmetry axis 12 and a lower portion whichincludes the bottom part of vessel 11. The lower portion of vessel 11has a tapered cross-section that diminishes towards the bottom of thevessel. The lower portion of vessel 11 has a side wall 14. Side wall 14has an outer surface which has a conical shape. The intersection of theouter surface of side wall 14 with a plane that passes through thelength axis 12 of vessel 11 forms a small angle with the length axis 12.

The vessels 11 of array 31 are arranged in vessel holder 13 with theirlength axis in a substantially vertical position.

The apparatus shown in FIGS. 1 and 2 further comprises an array 33 ofmagnets 15 each of which has a plane outer surface 16, and transportmeans 17 for moving each magnet of array 33 of magnets along a motionpath 25. As shown by FIG. 2, motion path 25 is for example a closedmotion path.

Transport means 17 comprise an array 34 of magnet holders 18, each ofwhich is adapted_for receiving and holding a substantial portion of amagnet 15, and a belt-drive 19 for moving the array 33 of magnet holders18 and thereby magnets 15 of array 33 of magnets 15 along motion path25.

FIG. 3 shows a first embodiment of an array 34 of magnet holders whichcomprises individual magnet holders 18 which are rigidly connected witheach other and each of which holds a magnet 15.

FIG. 4 shows a second embodiment of an array 34 of magnet holders whichcomprises a single body which has a plurality of cavities each of whichis adapted for holding a magnet 15.

Transport means 17 are adapted for moving each magnet 15 between a firstpredetermined position and a second predetermined position along motionpath 25. As shown by FIG. 2, the first predetermined position lies e.g.at about the same height as the central part of the lower portion of acorresponding vessel 11, and the second predetermined position is e.g.close to the bottom of that vessel 11.

The array 33 of magnets 15 and transport means 17 are so arranged withrespect to the array 31 of vessels 11 that while transport means 17 moveeach of magnets 15 along the portion of motion path 25 which extendsfrom the first predetermined position to the second predeterminedposition, the plane outer surface 16 of magnet 15 is in contact with aportion of the outer surface of side wall 14 of the lower portion of acorresponding vessel 11. Motion path 25 is so arranged that each magnet15 is moved downwards and towards the length axis 12 of a correspondingvessel 11 when magnet 15 is moved from said first predetermined positionto said second predetermined position along motion path 25.

As shown by FIGS. 5 and 6, each magnet holder 18 has a cavity 21 forreceiving a portion of a magnet 15.

In a certain embodiment a portion of magnet 15 is arranged in andsnuggly fits in a cavity 21 of magnet holder 18 as shown by FIG. 6. Inthis embodiment transport means 17 are so dimensioned that the initialtension of belt-drive 19 exerts on magnet 15 a force which presses itagainst side wall 14 and which is sufficient for ensuring contact of theplane outer surface 16 of magnet 15 and the outer surface of side wall14 of the lower portion of vessel 11, when the magnet 15 is locatedbetween belt-drive and vessel 11 and moves along motion path 25.

In another certain embodiment of magnet holder 18 shown by FIG. 5, thestructure of this holder includes leaf springs 22 and 23 arrangedbetween magnet 15 and magnet holder 18. In this embodiment the forcethat presses magnet 15 against the outer surface of side wall 14 of thelower part of vessel 11 is the sum of the force resulting from theinitial tension of belt drive 19 and the additional force exerted byleaf springs 22 and 23. The force resulting from this sum ensures a goodcontact of the plane outer surface 16 of magnet 15 and the outer surfaceof side wall 14 of the lower portion of vessel 11, when the latter islocated between belt-drive and vessel 11 and moves along motion path 25.

As illustrated by FIG. 5, in a certain embodiment magnet 15 has amagnetic axis 24 that forms an angle of 45 degrees with plane outersurface 16 of the magnet 15.

A certain embodiment of the apparatus described above with reference toFIGS. 1-6 further includes a waste connector or waste connecting device71 shown in FIGS. 1, 2 and 7 for connecting array 31 of vessels 11 to awaste container 75 which serves for disposing of waste liquids containedin vessels 11 of array 31 of vessels. Waste connector 71 comprises anupper part 73 and a lower part 74. Upper part 73 of waste connector 71includes the above-mentioned vessel holder 13 and cavities 72 each ofwhich is adapted for receiving a pipetting tip 61 during delivery ofwaste liquid from tip 61 to a waste chamber 75 fluidically connected tothe lower part 74 of waste connector 71. Waste connector 71 makes itpossible to deliver waste liquids which arise in various vessels 11 to awaste container 75. The transfer of a waste liquid arising in a givenvessel 11 to waste connector 71 and thereby to waste container 75 iscarried out with a pipetting tip 61 which is operatively associated withthat vessel.

FIG. 12 shows a certain embodiment of the lower part 74 of wasteconnector 71.

Lower part 74 of waste connector 71 has a plurality of bores 81, whichhave each an upper opening 82 adapted for receiving the tip 62 of apipetting tip 61 and lower opening 83 which fluidically connects thebore 81 with a channel 84. Each of bores 81 has a short vertical portionwhich extends downwards from the upper opening of the bore along avertical axis and a portion which extends along an axis which forms anangle α of about 20 degrees with the vertical axis. This structureoffers the advantage that a liquid jet delivered by a pipetting tip 61impacts on a surface which forms a slight angle with the axis of thejet. This prevents that waste liquid can splash outside of the boreduring delivery of waste liquid from the pipetting tip to the wasteconnector.

The above described structure of waste connector 71 shown by FIG. 12offers the following advantages:

-   -   splash of waste liquid is prevented during delivery of waste        liquid from the pipetting tip to the waste connector,    -   contamination between pipetting tips is prevented, and    -   contamination between pipetting tips and the waste connector is        prevented.

Lower part 74 of waste connector 71 has an outlet 85 located at thelowest point of channel 84. Liquid collected in channel 84 can thusleave waste connector 71 through outlet 85 and drop into a wastecontainer 75 following a path indicated by arrow 92.

In a certain embodiment of lower part 74 of waste connector 71 outlet 85is closed by a suitable closure (not shown) and lower part 74 has anoutlet 86 located close to the top portion of lower part 74 and achannel formed by channel portions 87 and 88 which are separated fromeach other by walls 89. In this embodiment, outlet 86 is fluidicallyconnected to an aspiration pump 91 which delivers liquid aspirated fromchannel 84 through channels 87, 88 and outlet 86 to waste container 75.Arrows 93 show the path followed by liquid aspirated from channel 84 anddelivered to waste container 75 as just described. This embodimentadvantageously removes aerosols that may arise in the interior of wastecontainer 71.

Example 4 Embodiment of an Array of Vessels Suitable for Use in anApparatus According to the Invention

An embodiment of array 41 of vessels suitable for use in an apparatus ofthe kind described above with reference to FIGS. 1-7 is describedhereinafter with reference to FIGS. 8 to 11.

FIG. 8 shows a perspective view of a vessel array 41 according to theinvention with pipetting tips 61 inserted in respective vessels 51 eachof which is adapted for receiving a pipetting tip.

FIG. 9 shows a second perspective view of a vessel array 41 according tothe invention.

FIG. 10 shows a cross-sectional view of vessel array 41.

FIG. 11 shows perspective view of a pipetting tip 61 shown in FIGS. 1and 2.

Vessel array 41 comprises a first row 31 of vessels 11 for receivingsamples and a second row 43 of vessels 51 each of which is adapted forreceiving a pipetting tip 61.

Vessel array 41 further comprises an upper part 45 which hasapproximately a cuboid shape and is divided in compartments 46. Eachcompartment 46 has a substantially cuboid shape and being divided incompartments 46 bottom wall 48 and side walls 48. A vessel 11 forreceiving a sample extends downwards from an opening 52 in the bottom ofwall 48 of each compartment 46. A vessel 51 for receiving the lower partof a pipetting tip 61 extends downwards from an opening 53 in the bottomof wall 48 of each compartment 46.

Each compartment 46 has a back side wall 55 and a front side wall 54located in face of the back side wall. Neighboring compartments 46 areseparated from each other by side walls 47 which extend each between aback side wall and a front side wall of a compartment.

Front side wall 54 of each compartment 46 has a central opening 56 whichallows the passage of the tip 62 of a pipetting tip 61 when the latteris moved from a position within the array of vessels 41 to a positionoutside the array of vessels 41, e.g. when after aspiration of wasteliquid from a vessel 11, pipetting tip 61 is moved away from vessel 11and towards a position located in waste connector 71, e.g. the positionof pipetting tip 61 shown in FIG. 7.

In a certain embodiment of vessel array 41, the upper part 45 thereof ismade by injection molding of a first plastic material, e.g. ofpolystyrene, and the first and second rows 31, 43 of vessels are made byinjection molding of a second plastic material, of polypropylene, andthe material of the upper part 45, e.g. polystyrene, is more rigid thanthe material of the first and second rows 31, 43 of vessels, e.g.polystyrene. The advantage of this selection of materials is that theresulting structure of vessel array is less prone to getting deformeddue to the operation conditions, and due e.g. to changes of temperatureof the environment.

Example 5 Second Embodiment of a Method According to the Invention

A method for separating magnetic particles from a liquid which containssuch particles can be carried out according to the invention with theapparatus embodiment of example 3 described above with reference toFIGS. 1 to 7 and with the array of vessels of example 4 described abovewith reference to FIGS. 8 to 11.

According to this method an array 33 of magnets 15 each of which has aplane outer surface 16 is moved automatically so that each of magnets 15is thereby moved along a motion path 25 so that over a portion of motionpath 25 which extends from the above-mentioned first predeterminedposition to the second predetermined position, the plane outer surface16 of each magnet 15 is in contact with a portion of the outer surfaceof side wall 14 of the lower portion of vessel 11, and each magnet 15 ismoved downwards and towards the length axis 12 of a vessel 11, when itis moved along the above mentioned portion of motion path 25.

In a certain embodiment a force is exerted on each magnet 15 of thearray 33 of magnets in order to press the plane surface 16 of eachmagnet on the outer surface of the side wall 14 of the lower part of acorresponding vessel 11 while magnet 15 is moved along theabove-mentioned portion of motion path 25.

In a certain embodiment motion path 25 is a closed motion path.

Example 6 Embodiment of a System in which the Above MentionedApparatuses and Methods are Used

A system of this kind comprises a conveyor (not shown in the attacheddrawings), e.g. a conveyor adapted for moving vessel array in threedirections X-, Y, Z which are orthogonal to each other. The latterconveyor serves for automatically transporting an array of vessels 41according to Example 4 and positioning that array in vessel holder 13 inthe position shown in FIGS. 1 and 2. With array 41 of vessels in thatposition pipetting operations are carried out in each of vessels 11 witha corresponding pipetting tip 61 which when not in use rests inserted ina vessel 51 adjacent to vessel 11.

When waste liquid in a vessel 11 has to removed, pipetting tip 61 isautomatically transported into vessel 11 for that purpose, the wasteliquid is aspired into pipetting tip 61, this tip is then automaticallytransported towards waste connector 71 and placed there in the positionshown in FIG. 7. With pipetting tip 61 in that position the waste liquidis ejected from the tip and into a collecting chamber inside wasteconnector 71. During transport of pipetting tip 61 from vessel 11 towaste connector 71 the lower part of tip 61 passes through one of theopenings 56 in the back side wall 55 of vessel array 41.

Although certain embodiments of the invention have been described usingspecific terms, such description is for illustrative purposes only, andit is to be understood that changes and variations may be made withoutdeparting from the spirit or scope of the following claims.

While the foregoing invention has been described in some detail forpurposes of clarity and understanding, it will be clear to one skilledin the art from a reading of this disclosure that various changes inform and detail can be made without departing from the true scope of theinvention. For example, all the techniques and apparatus described abovecan be used in various combinations. All publications, patents, patentapplications, and/or other documents cited in this application areincorporated by reference in their entirety for all purposes to the sameextent as if each individual publication, patent, patent application,and/or other document were individually indicated to be incorporated byreference for all purposes.

What is claimed is:
 1. An apparatus for separating magnetic particlesfrom a liquid which contains said particles, said apparatus comprising:(a) a vessel array comprising a plurality of elongated vessels, eachelongated vessel comprising a length axis, an upper portion, a lowerportion comprising a central part and a bottom part, and a side wallextending between the upper and lower portions, wherein the lowerportion comprises a cross-section tapered in diameter towards the bottompart of the vessel relative to a diameter of the upper portion, and theside wall includes an outer surface comprising a conical shape, whereinsaid vessel array comprises a plurality of vessel compartments, eachcomprising a compartment vertical length axis that is substantiallycoincident with the length axis of the elongated vessel, such that theplurality of elongated vessels are arranged in the vessel array in asubstantially vertical position; (b) an array of magnets, wherein eachmagnet is operably associated with a vessel compartment of the array,each magnet comprising a plane outer surface in communication with theouter surface of the side wall of the vessel; and (c) a transport meanscomprising a belt drive, wherein the array of magnets is rotatablymounted to the belt drive and the belt drive is configured to move thearray of magnets along a motion path positioned between first and secondpredetermined positions of said apparatus, wherein the firstpredetermined position is substantially aligned with the central part ofthe lower portion of the elongated vessel and the second predeterminedposition is substantially aligned with the bottom of the elongatedvessel, and the motion path is substantially parallel with the lengthaxis of the elongated vessel, and said belt drive is configured to movesaid array of magnets along said motion path such that over at least aportion of said motion path, said plane outer surface of said magnet isin contact with at least a portion of said outer surface of said sidewall of said vessel.
 2. The apparatus of claim 1 wherein the belt drivefurther comprises one or more tooth wheels in operable communicationwith a tension pulley.
 3. The apparatus of claim 1 wherein the transportmeans is configured to move the array of magnets downwards from thefirst to the second predetermined positions.
 4. The apparatus of claim 1wherein said vessel array comprises an upper part having a substantiallycuboid shape.
 5. The apparatus according to claim 1, wherein saidtransport means further comprises a magnet holder having a cavityadapted to receive a portion of the magnet upon rotatable engagement ofthe transport means along said motion path.
 6. The apparatus accordingto claim 5, wherein the magnet holder further comprises one or moresprings positioned in the cavity and capable of exerting a predeterminedforce on said magnet and said outer surface of the side wall when saidmagnet is moved over said portion of said motion path.
 7. The apparatusof claim 5 wherein the magnet holder comprises a body comprising aplurality of individual magnet holders.
 8. The apparatus of claim 7wherein the plurality of individual magnet holders are rigidly connectedin the body.
 9. The apparatus according to claim 1, wherein the motionpath is a closed motion path.
 10. The apparatus according to claim 1,wherein the magnet has a magnetic axis that forms an angle of about 45degrees with the plane outer surface of the magnet.